1. 醫學系「免疫與感染學 V 」模組
Inflammatory Diseases of Muscle
-- Polymyositis & Dermatomyositis
魏正宗
中山醫學大學附設醫院
過敏免疫風濕科主任、中藥臨床試驗中心主任
Tel: 04 24729595 ext 34314; Email: wei3228@gmail.com

2. 學習目標
 Inflammatory Diseases of Muscle

Definition
Pathophysiology
 Clinical manifestations
 Diagnosis

Treatment

Prognosis


3. Weakness, etiologies:
Nerve
2. Neuromuscular junction
3. Muscle
4. Psychogenic
1.

5. 5 subsets of inflammatory myopathies

7. Proximal muscle weakness
 Shoulders, thighs, trunk and pelvic girdle
muscles are most affected.
 Never facial and ocular muscles
 Esophagus, pharynx and respiratory
muscles may involved.
 May arthralgia and myalgia

8. Heliotrope sign

10. Heliotrope sign:

11. 皮肌炎 Dermatomyositis

12. V-sign: rash over anterior neck and upper chest

14. Gottron’s sign

15. Gottron’s sign

16. Gottron’s sign and periungual erythema

17. Periungual erythema

18. Vasodilatation in capillary microscope

19. Mechanist hand

21. Lab
 Muscle enzyme–



Creatine Kinase
Indicator of disease activity and severity
May be normal in very early, remission or
atrophy pts.
CK rise weeks preceding clinical evidence of
muscle weakness
 Other muscle enzymes: ALT, AST, LDH,
aldolase

22. Autoantibodies


ANA, anti-nuclear antibody ~80%
Anti-ENA, extractable nuclear antigen
 Anti-Jo-1
• most common myositis-specific autoantibody ~30%.
• anti–tRNA synthetase syndrome: Lung iinvolvement, Raynaud's
phenomenon

Anti-SRP antibodies
• signal recognition particle (SRP) : translocation of newly
synthesized proteins into the endoplasmic reticulum.
• only in polymyositis with severe myopathy and aggressive
disease

Anti-Mi-2 antibodies
•
•
directed against a helicase involved in transcriptional activation
associated with the relatively acute onset of classic
dermatomyositis with erythroderma and the shawl sign

24. EMG of PM/DM
•
Triads in 40% of pts:
polyphasic, small
amplitude, short
duration
•
Chracteristic but not
diagnostic
•
15% of pts may be
normal EMG

25. Muscle biopsy of polymyositis
•Focal and endomysial
infiltration of T cell, esp.
CD8, with small number
of macrophage
•Muscle fiber
degeneration and
atrophy

26. Muscle biopsy of dermatomyositis
 Peri-vascular
infiltration of
inflammatory cells,
composed of
higher percentage
of B cell and CD4
T cells.

27. Image study
 MRI
 Muscle scan

28. Other systemic features of idiopathic
inflammatory myopathy

Esophageal




Gastrointestinal




Uncoordinated peristalsis
Reflux
Dysphagia
Uncoordinated peristalsis
Delayed gastric emptying
Ischemic necrosis
Endocrine


Autoimmune thyroiditis
“euthyroid sick “syndrome

29. Cardiopulmonary features
 Cardiovascular
manifestations




Raynaud’s
phenomenon
Myocarditis
Conduction
abnormalities
Heart failure
 Pulmonary
manifestation



Diffuse interstitial
disease
Pulmonary hypertension
Bronchiolitis obliterans
organizing pneumonia

31. Raynaud’s phenomenon

32. Diagnostic criteria of
Dermatomyositis/Polymyositis
1.
2.
3.
4.
5.
Proximal muscle weakness
Increased muscle enzyme(CK)
EMG findings
Muscle biopsy
Skin lesion -- Gottron's sign, heliotrope sign

33. Myositis in autoimmune diseases
 Common in scleroderma, SLE, MCTD,
Sjogren’s syndrome
 Sometimes in RA, Adult Still’s disease,
Vasculitis syndrome. Esp. Wegner’s
granulomatosis and polyarteritis nodosa.

34. Myositis association with malignancy
 Frequency of malignancy in myositis
derived from 5%-35%
 Most common sites: NPC, Lung, GI, Gyn
 Work-up: careful history and PE and
routine laboratory, tumor markers, image
studies

35. Approaching DM/PM

36. Management of PM/DM
 Corticosteroid alone (60-100 mg/day)
 Immunosuppressive agents in
conjunction with corticosteroid
therapy
Hydroxychloroquine (100-200 mg/day)
 Azathioprine (2 mg/kg/d-50 mg/d)
 Methotrexate (MTX 7.5-25 mg/wk)

Cyclphosphamide (50-200mg/d)

Cyclosporin A (7.5-10mg/kg/d)


37. Steroid in Myositis
 prednisolone1-2 mg/kg/day or
methylprednisolone pulse therapy
 90% improved after steroid therapy in
weeks to months
 50-75% had complete remission
 Need slowly tapering of steroid
 Tends to occur when taper steroid

38. Resistant disease
- Rituximab (anti-CD20)
-
Intravenous immune globulin (IVIG)
Mycophenolate mofetil
Tumor necrosis factor inhibitors

39. Unfavorable Outcome








Malignancy
Other collagen vascular disease
Raynaud’s phenomenon
Dysphagia
Older age
Severe or refractory muscle disease
Cardiac involvement
Pneumonitis/Interstitial lung disease

40. Conclusions
 Workup of muscle weakness
 Differential diagnosis of myopathy
 Classification and diagnostic criteria of
dermatomyositis and polymyositis
 Has specific autoantibodies
 Can be controlled by steroid and steroidsparing agents

41. References
 eMedicine : Polymyositis/Dermatomyositis
http://www.emedicine.com/neuro/topic85.htm
 UpToDate : Polymyositis/Dermatomyositis
http://www.lib.csmu.edu.tw/overlib/2305.php